The present invention relates to test equipment and, more particularly, to a measurement system that samples a signal, stores data representative of the signal in memory, and processes the data in a manner that facilitates fast evaluation of the signal or characteristics thereof.
Electronic measurement devices are widely used by engineers and technicians across many industries for the purpose of analyzing, for example, electronic and/or optical signals. The speed and accuracy of such a measurement device has a direct impact on the timeliness within which a problem may be analyzed and addressed.
In recent years, there has been a growing need for measurement devices having the ability to store large volumes of data (i.e., a data record) representing a signal under analysis. These types of measurement devices are said to provide xe2x80x9cdeep memory recordsxe2x80x9d representative of a signal under analysis. The greater the size of the data record representing the signal under analysis, the greater the ability of the measurement device to provide for display and measurement of the characteristics of a signal under analysis. Examples of measurement devices incorporating a deep memory record include the Hewlett Packard model 54622D oscilloscope, as well as the Agilent Infiniium oscilloscope models 54830D, 54831B and 54832B. These types of oscilloscopes are commonly referred to as deep memory oscilloscopes.
Unfortunately, large data records require time for the measurement device to process in order to carry out a desired measurement/evaluative process. Examples of relevant measurements/evaluative processes that may be carried out by the measurement device include edge measurements to determine rise time, fall time, period, frequency, duty-cycle, positive and negative pulse widths, delay between edges, phase, the time that an edge reaches a particular value, as well as many other types of measurements.
Once a portion of the signal under analysis has been identified as being of interest for evaluation, the entire data record stored in memory is accessed and acted on for purposes of carrying out the desired evaluation/measurement. The portion of the signal to be analyzed may be identified by a user or by an algorithm that processes the data in a particular manner to find the portion of the signal of interest. Although only a portion of the signal under analysis is relevant and required to carry out the desired evaluation/measurement, the entire data record (and not just relevant portions thereof) is retrieved from memory and processed to carry out the desired measurement/evaluation. Processing all of the data in the data record consumes a large amount of time and computational resources.
Another known deep memory oscilloscope runs edge measurements on a compressed data record. Although the compressed data record is smaller than the original deep memory data record, and thus can be processed faster, the edge measurements are not as accurate as when the entire deep memory data record is used to locate and measure an edge.
It would be desirable to provide a measurement system that is capable of processing large volumes of data, such as deep memory data, for example, in such a way that a signal, or a portion thereof, can be evaluated quickly and with relatively low processing overhead. Accordingly, a need exists for a measurement system that is capable of sampling and evaluating a signal efficiently with relatively low computational intensity, thereby enabling the evaluation process to be performed quickly without over-utilization of computational resources.
The present invention provides a measurement system for analyzing data values that are stored in memory and that represent a sampled electrical signal under analysis (SUA). Each of the data values represents the SUA at respective points in time over a time interval during which the SUA was sampled. The stored data values constitute a main data record. The system includes processing logic that is configured to generate at least a first reduced data record from the main data record. The first reduced data record comprises a subset of the data values of the main data record. The first reduced data record is processed by the processing logic to obtain boundaries in the main data record that correspond to a bounded region of the SUA that may or may not include an edge (i.e., a voltage transition). The data values within these boundaries correspond to the first reduced data record. Because only these data values are used to locate the edge, as opposed to using all of the data values of the main data record, the edge can be located quickly and easily.
In order to analyze the edge after it has been located, the processing logic processes a second set of data values of the main data record, which may be the entire main data record or a subset thereof. The second set of data values includes one or more data values of the main data record that are not included in the first set of data values, and is larger than the first set of data values. Using a larger number of data values to evaluate the edge ensures that a sufficient number of data values are used so that the evaluation is precise.
If desired or deemed necessary, additional reduced data records may also be generated from the main data record and processed to more closely locate the edge. Once the final bounded set of data values to be used in the evaluation has been obtained, preferably all of the data values of the main data record that are within the boundaries associated with the bounded set are processed to evaluate the SUA.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description.